Washington CNN  — 

President Joe Biden is more isolated than he has ever been, with many senior-ranking White House and campaign officials now privately believing that he must abandon his campaign for a second term – and soon.

“The next 72 hours are big,” one Democratic governor in close touch with party officials relayed to aides on Thursday. “This can’t go on much longer.”

In interviews with CNN, more than two dozen sources familiar with the dynamics inside the West Wing and campaign said there is now widespread acceptance that Biden remaining in the 2024 race is wholly untenable.

“Everyone is saying it privately,” one senior Democrat said. “People see and feel the walls closing in.”

Another top Democrat close to the White House described Biden as having become “exceptionally insulated and isolated” since the CNN presidential debate on June 27.?Multiple sources said some of the most senior advisers to Biden – including adviser Anita Dunn, attorney Bob Bauer and campaign chair Jen O’Malley Dillon – faced the ire of the president’s family in the aftermath of the debate.

That has only had the effect of making Biden’s inner circle of advisers with free access to the president – which had already been famously small and impenetrable – even tighter.

Three weeks after his disastrous debate performance that shocked even his closest aides, friends and Democrats across the party, a stunningly small number of his most loyal aides – chief among them, his decadeslong advisers Mike Donilon and Steve Ricchetti – and members of the Biden family appear dug in along with the president. That tight circle has alarmed many Democrats who are questioning whether Biden is receiving realistic data about the plight of his candidacy.

Deputy White House chief of staff Annie Tomasini, a longtime aide to the Bidens, joins Donilon and Ricchetti in forming a protective bubble around the president. Anthony Bernal, chief of staff to Jill Biden, has grown even more powerful during the deepening crisis and has tamped down any signs of dissent, two sources say, reporting any naysayers to the first lady. One person close to the inner circle of advisers said Tomasini plays no role in deciding who the president sees and speaks to.

Ricchetti is more clear-eyed about the challenges facing Biden, two people familiar with the dynamic inside the West Wing said, largely because he remains the point person for lawmakers trying to send a message to the president. Amid a fury of speculation about Biden’s future, senior-most West Wing advisers to Biden told CNN Thursday night that they have had no discussions among themselves – or with Biden – about him dropping out of the presidential race.

In response to questions about this story, White House spokesperson Andrew Bates said Biden is “proud of the well-rounded team he has built.”

“He has not made changes to the group of advisers he consults, who he trusts because they’ve demonstrated the integrity to tell the truth and keep the wellbeing of the American people front of mind,” Bates said.

Campaign spokesman Kevin Munoz said, “Here in HQ, we’re working really hard because on winning campaigns, you work really hard.?There’s an immense sense of pride across our office, because we know how important and critical that work we are doing here is for the fate of our democracy.”

Multiple sources also told CNN that the president’s recent response to bad polls has been to cast doubt on whether there is anybody else who would perform stronger than him. Meanwhile, meetings and phone calls with anyone that might come bearing bad news appear to have paused.

“The phones just kind of stopped ringing,” is how one senior Democrat put it.

CNN previously reported that in a tense conversation between former House Speaker Nancy Pelosi and Biden within the last week or so where the two disagreed over polling, Pelosi asked for Donilon,?a former pollster,?to join the phone call to go over the data.?A Pelosi spokesperson said Thursday the “feeding frenzy from the press based on anonymous sources misrepresents any conversations the speaker may have had with the president.”

“He doesn’t want to hear from anyone. He wants to hear from Mike Donilon and Steve,” one top Democrat close to the White House said.

One person close to Biden’s inner circle insisted that Donilon and Ricchetti have been presenting a range of views to Biden and that the president himself has been speaking directly with numerous party officials to hear their feedback.

And in a meeting with top House Democrat Hakeem Jeffries, Biden aggressively challenged the notion that Jeffries’ colleagues wanted him to step aside, according to a source briefed on the discussion.

Unlike on Capitol Hill, where Democratic lawmakers have slowly begun to publicly voice their concerns – so far, 20 House Democrats have come out to call on Biden to drop out – White House and campaign aides have had little choice but to continue doing their day jobs. As Biden and his campaign aides continue to publicly insist that the president is not going anywhere, the mood in many corners of the White House and campaign has been of deep despair.

“There is a lot of people who tell themselves – it is my job to do this,” one Democrat close to the White House said. “But privately, they feel differently.”

Biden’s deputy campaign manager Quentin Fulks?on Thursday said the campaign is “not working through any scenarios” where?Biden?is not the presidential nominee.

“Our campaign is not working through any scenarios where President?Biden?is not the top of the ticket. He is and will be the Democratic nominee,” he said during a DNC news conference in Milwaukee.

Biden’s stunningly halting debate performance – and the downward spiral of his candidacy since – has sparked serious discontent inside the White House, with plenty of fingers pointed at senior advisers. Officials in and out of the administration have quietly questioned the intentions of those in the president’s inner circle –?and whether their choice to stay-the-course-at-all-costs stems from a fear of acknowledging they misread the situation or a desire to preserve their proximity to power.

“This decision is not just about Biden,” a former aide who had worked with Biden for decades told CNN. “There are other senior advisers who are considering whether they played the right role in this.”

The frustration with the president’s advisers has permeated all levels of the White House as staff wrestles with a lack of information and decisions about their own professional future.

“Staff in general are just over the leadership here,” one White House official said.

Multiple former administration officials have told CNN that there has been an uptick in resumes on their desks in recent weeks, as their former colleagues are starting to look for an exit plan in the private sector.

As Biden spent Thursday out of sight, recovering from Covid-19 at his beach house in Delaware, he has been described by those who have spoken to him as being “receptive” to arguments to step away from his reelection bid, a senior Democratic adviser told CNN.

Biden is in a “contemplative stage” as he isolates in Rehoboth Beach. A source familiar with the president’s mindset?said?that he is “thinking things through” and “deliberating” about how to proceed?with his reelection campaign?while he’s in isolation. He has privately acknowledged to others that there is a limited path, given the all the unfavorable data, the source said.

This source said it’s unlikely the president will make any sort of announcement before the weekend and cautioned that anyone who thinks they know what Biden will ultimately do doesn’t actually know.

That makes it an open question – frustratingly so, in the eyes of many Democrats – whether Biden has come to any new decisions about his future. But even if he does heed the calls to step aside, a cascading series of events would be set into motion that officials would need time for which to prepare.

Inside the White House, senior administration officials are bracing for Republicans to call for Biden to resign the presidency if he doesn’t seek reelection. These arguments are one of the many complicating factors surrounding Biden’s decision.

With Biden’s political future on the brink, the White House is fielding a steady stream of letters, telephone calls and message from Americans, too, from Democratic voters like Terri and John?Hale.

“It’s with utmost respect that we offer this conclusion – you cannot win this race,” the Hales, retirees from Ankeny, Iowa, wrote in a letter to the White House obtained by CNN. “Not because you are not the better man, but because the public – rightly or wrongly – now sees your age and perceived limitations as the main issue in the campaign.”

CNN’s Pamela Brown contributed to this report.